The two main causes of blindness in the western world are diabetic retinopathy and glaucoma.
One of the most important pathologies of diabetic retinopathy is macular edema. Over a lifetime, about 30% of the people with diabetes will develop macular edema. Nonproliferative diabetic retinopathy with Clinically Significant Macular Edema (CSME) includes either (a) thickening of the retina at or within 500 microns of the center of the macular or (b) hard exudes at or within 500 microns of the center of the macular if associated with thickening of the adjacent retina (not residual hard exudates remaining after the disappearence of retinal thickening) or (c) a zone or zones of retinal thickening 1 disk area or larger, any part of which is within 1 disk diameter of the center of the macula. Patients with CSME should be considered for treatment.
The assessment of retinal thickening by slit lamp biomicroscopy and/or stereo fundus photography is often difficult, not accurate, and of questional reliability. Moreover, the current methods typically necessitate a time consuming involvement of a highly skilled observer. Currently there is no commercially available method, capable of detecting and mapping quantitatively retinal thickening. Thus accurate assessment of CSME in patients remains subjective even though the clinical criteria of CSME are quantitative. The present invention enables the necessary objective quantitative measurements to be performed.
Loss of vision from glaucoma is largely preventable through early diagnosis and therapy. While the level of Intra occular Pressure (IOP) is strongly correlated with the risk of glaucoma optic nerve damage, a substantial proportion of patients with glaucoma (one sixth or more) have not had demonstratable or repeated elevations of IOP above 21 mm Hg. Conversely, many individuals with IOP repeatedly above 21 mm Hg do not have, and may never develop, optic nerve damage during their lifetime.
Screening procedures for identifying patients at significant risk for glaucomatous visual field loss are most effective when IOP measurements are combined with an assessment of the optic nerve and a review of other potential occular and systemic risk factors. This approach is already part of the "Comprehensive Adult Eye Examination", which may constitute the single most important screening/diagnostic setting to identify patients at risk and a subset of those at particularly "high risk" for glaucoma.
Visible structural alterations of the optic nerve or nerve fiber layer frequently occur before visual defects can be measured, even with the most sensitive current techniques. While measures of both structure and function are important to detect early glaucomatous damage, careful and repeated examination of the optic nerve and nerve fiber layer may provide the earliest signs of damage by demonstrating progressive damage before definitive visual field abnormalities appear. The present invention allows an objective method for nerve fiber layer damage assessment.